Ühel kenal päeval, T, 2006-08-01 kell 10:54, kirjutas Andrew Dunstan: > Gregory Stark wrote: > > > > I looked a while back and was suspicious about the actual hash functions > > too. > > It seemed like a lot of them were vastly suboptimal. That would mean we're > > often dealing with mostly empty and mostly full buckets instead of well > > distributed hash tables. > > > > > > > > This is now sounding like a lot of low hanging fruit ... highly > performant hash indexed tables could possibly be a very big win. >
Are you sure about the badness of our hash functions ? I just tested and hashtext(text) has about 1.4% of collisions on about 120M distinct texts, which is not bad considering thet total space for hashes is 4G, meaning that 120M covers itself already 3% of possible hash space. -- ---------------- Hannu Krosing Database Architect Skype Technologies OÜ Akadeemia tee 21 F, Tallinn, 12618, Estonia Skype me: callto:hkrosing Get Skype for free: http://www.skype.com ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
